This is news? I thought people knew T-Pain could sing without Auto-Tune, I've heard him without it during live performances years back. I even remember him in a interview with Angie Martinez saying that the Epiphany album actually means that he came to an epiphany that auto-tune was more interesting than using his own voice when making music and he was right. He became very successful because of it until everyone hopped on the bandwagon and saturated the industry with the sound.
Of course I've never seen him do anything this extensive, singing acapella with only some keys as the musical back drop.